For example, vehicles such as trucks, buses, and construction machines use compressed air delivered from the compressor, which is directly connected to the internal combustion engine, in order to control systems such as brakes and suspensions. In any systems including brakes and suspensions, compressed air delivered from the compressor includes water contained in the atmosphere. When the compressed air containing water enters the systems, it may become a cause of an operation defect of the systems. For this reason, an air dryer is provided downstream of the above-mentioned compressor to remove water from the compressed air.
The air dryer executes a loading mode operation for removing water by allowing compressed air to pass through a desiccant and an unloading mode operation for regenerating the desiccant by discharging water trapped by the desiccant to the outside. The air discharged from the air dryer during the unloading mode operation contains oil together with water. Thus, considering the burden on the environment, it has been proposed to provide an oil separator for separating and recovering oil from the air discharged from the air dryer.
The oil separator separates gas and liquid by allowing air containing water and oil to strike an impingement member. Such a gas/liquid separation causes air, or gas from which water and oil have been removed, to be expelled to the outside and water and oil that have been separated from the air to be recovered in the oil separator as collected liquid (for example, see Patent Document 1).